Patch "zram: avoid access beyond the zram device" has been added to the 3.4-stable tree

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This is a note to let you know that I've just added the patch titled

    zram: avoid access beyond the zram device

to the 3.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     zram-avoid-access-beyond-the-zram-device.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 624d1705fa1d6e4c647ca5859ecd921748bd85bf Mon Sep 17 00:00:00 2001
From: Jiang Liu <liuj97@xxxxxxxxx>
Date: Fri, 7 Jun 2013 00:07:26 +0800
Subject: zram: avoid access beyond the zram device

From: Jiang Liu <liuj97@xxxxxxxxx>

commit 12a7ad3b810e77137d0caf97a6dd97591e075b30 upstream.

Function valid_io_request() should verify the entire request are within
the zram device address range. Otherwise it may cause invalid memory
access when accessing/modifying zram->meta->table[index] because the
'index' is out of range. Then it may access non-exist memory, randomly
modify memory belong to other subsystems, which is hard to track down.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/zram/zram_drv.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -535,13 +535,20 @@ out:
  */
 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 {
-	if (unlikely(
-		(bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
-		(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
-		(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
+	u64 start, end, bound;
 
+	/* unaligned request */
+	if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
+		return 0;
+	if (unlikely(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
+		return 0;
+
+	start = bio->bi_sector;
+	end = start + (bio->bi_size >> SECTOR_SHIFT);
+	bound = zram->disksize >> SECTOR_SHIFT;
+	/* out of range range */
+	if (unlikely(start >= bound || end >= bound || start > end))
 		return 0;
-	}
 
 	/* I/O request is valid */
 	return 1;


Patches currently in stable-queue which might be from liuj97@xxxxxxxxx are

queue-3.4/zram-avoid-invalid-memory-access-in-zram_exit.patch
queue-3.4/zram-destroy-all-devices-on-error-recovery-path-in-zram_init.patch
queue-3.4/zram-avoid-access-beyond-the-zram-device.patch
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